There is illustrated in FIG. 1, a schematic view of the way in which a speaker is mounted in a conventional television. As shown in FIG. 1, the television has a housing front portion 1 for accommodating a speaker grill 2. A speaker 5 having a diaphragm 4 is mounted at the rear of the speaker grill 2 through a speaker frame 3. A plurality of buttons 6 are mounted on the housing front portion 1.
The frame 3 supports the speaker 5 and transfers vibrations of the speaker 5 caused by the vibration of a moving coil and a diaphragm 4 therein to the housing front portion 1 to thereby cause a resonance phenomenon. Due to this resonance, vibrations and noises occur mainly at the housing front portion 1.
FIG. 2A is a graph of accelerations measured at a connecting spot between the speaker and the housing front portion of the television and FIG. 2B shows a graph of displacements measured at the connecting spot between the speaker and the housing front portion of the television. As shown in FIGS. 2A and 2B, the connecting spot most severely vibrates when the frequency of the speaker 5 is 168 Hz.
FIG. 3 represents a graph of sound pressures measured at an outer spot of the television. The largest sound pressure is observed when the frequency of the speaker 5 is 216 Hz. The sound pressure is generated not by the vibration of the speaker 5 but by the vibration of the television.
Consequently, the resonance frequencies of the speaker 5 and the housing front portion 1 are 168 Hz and 216 Hz, respectively. The frequency of the housing front portion 1 is larger at the face and bottom panels of the housing front portion 1, and the vibration of the buttons 6 are caused by the face and the bottom panels vibrating. Finally, noises are generated as a result of the interferences between the vibration of the buttons 6 and the vibration of the housing front portion.